PRE-TREATMENT , SURFACE PREPARATION , DEGREASING & CLEANING
Vapour degreasing - A simple guide for production engineers
This simple guide for production engineers discusses why vapour degreasing is the most effective and economical process for cleaning of manufactured components .
Now is a good time to review your existing cleaning processes or upgrade current equipment . In the autumn Budget 2021 , the Chancellor , Rishi Sunak , announced an extension of the temporary increase in Capital allowances which allow the cost of capital assets to be written off against taxable income . The 130 % super-deduction and 50 % first-year allowance are very generous but only available for a short time . This will allow companies to not only lower their corporation tax bills but improve productivity and reduce operating costs for cleaning processes .
Vapour degreasing is the simplest but most effective degreasing and cleaning process which , until recently , has been subject to little change since it was first invented in the early part of the last century . This is a very mature chemical technology which legislation is now effecting changes so fundamental that the more accurate name for the process “ Condensation Cleaning ” should be used to reflect the improvements in equipment design , chemistry , reduced emissions , economies in usage of solvents and the subsequent environmental acceptability compared to the open topped tanks so ubiquitous in factories and workshops worldwide . The alternatives in equipment design offer differences in technology , which guarantee the continuing use of this process in the future , need to be considered and understood .
The cleaning tank in the corner of most engineering shops hides a very well researched process using sophisticated chemistry . Its popularity is in its simplicity . The tank sump is heated , fitted with cold coils around the internal surfaces at the top to retain the vapour . Fill to a few centimetres with a non-flammable solvent able to dissolve contaminants , boil to form a vapour 3 to 4 times heavier than air to fill the tank . Hot solvent vapour condenses on the cooler target parts at workplace temperature . The hot liquid solvent dissolves oil and grease and other contaminants . Used solvent returned to the sump revaporises continuing the cycle until parts have achieved the same temperature as the vapour when , with no further condensation , the process is complete . Simple but perfect . Highly
productive and economical , parts removed from the cleaning process are clean , warm , and dry in 5 to 10 minutes .
Historically chlorinated hydrocarbons have been the solvents of choice for the “ Condensation Cleaning ” process . Compatible with most materials of manufacture , stable in constant use , producing a non-flammable saturated vapour heavier than air at a temperature greater than ambient .
In Europe , the United States and in other advanced industrialised economies increasingly stringent legislation to control emissions of VOCs , especially solvents , has led to new formulations for paints and other coatings where water replaces most of the solvent . In the early days the quality of water-based paints was not as good as traditional solvent-based coatings , but innovation has driven the development of new polymers with results as good as , if not better than , the solvent-based originals .
CONTINUED ON PAGE 40
38 MARCH 2022 read online : www . surfaceworld . com